BackgroundLarge granular lymphocyte leukemia is a rare lymphoproliferative disorder associated with autoimmune diseases and impaired hematopoiesis. This study describes the clinical and biological characteristics of 229 patients with T-cell or NK-cell large granular lymphocyte leukemia. Design and MethodsThe diagnosis was based on a large granular lymphocyte expansion (> 0.5¥10 9 /L) lasting more than 6 months. Monoclonal T-cell receptor γ gene rearrangement was detected in all the cases of T-cell large granular lymphocyte leukemia. Patients with chronic NK-cell lymphocytosis had an indolent disease, while those with multiorgan large granular lymphocyte infiltration and an aggressive clinical disease were considered to have NK-cell large granular lymphocyte leukemia. ResultsThe diagnosis of T-cell large granular lymphocyte leukemia was confirmed in 201 cases, chronic NK-cell lymphocytosis in 27 cases and NK-cell large granular lymphocyte leukemia in one case. Associated auto-immune diseases or other neoplasms were present in 74 and 32 cases, respectively. One hundred patients (44%) required treatment, mainly for neutropenia-associated infections (n=45), symptomatic auto-immune diseases (n =24), transfusion-dependant anemia (n=18), and other causes (n=13). Patients were treated with steroids (n= 33), methotrexate (n=62), cytoxan (n=32), or cyclosporine (n=24) either as first-, second-, third-or fourth-line therapy. The overall response rate at 3 months and complete response rate for the various treatments were as follows: steroids (12% and 3%), methotrexate (55% and 21%), cytoxan (66% and 47%), cyclosporine (21% and 4%), respectively. Four out of 13 patients responded to splenectomy. Eleven out of 15 patients responded to cytoxan after methotrexate treatment had failed. The mean number of treatments was 3.4 (range, 1-7). There were 15 large granular lymphocyte leukemia-related deaths. ConclusionsPatients with T-cell large granular lymphocyte leukemia and chronic NK-cell lymphocytosis have similar clinical and biological features and responses to treatment. First-line therapy with cytoxan should be tested in a prospective trial.Key words: large granular lymphocyte leukemia, LGL leukemia, NK lymphocytosis.Citation: Bareau B, Rey J, Hamidou M, Donadieu J, Morcet J, Reman O, Schleinitz N, Tournilhac O, Roussel M, Fest T, and

M-MDSCs and G-MDSCs strongly contribute to T-cell dysfunction in patients with sepsis. More specifically, G-MDSCs producing arginase 1 are associated with a higher incidence of nosocomial infections and seem to be major actors of sepsis-induced immune suppression.

In diffuse large B-cell lymphoma (DLBCL), the number of circulating monocytes and neutrophils represents an independent prognostic factor. These cell subsets include monocytic and granulocytic myeloid-derived suppressor cells (M- and G-MDSCs) defined by their ability to suppress T-cell responses. MDSCs are a heterogeneous population described in inflammatory and infectious diseases and in numerous tumors including multiple myeloma, chronic lymphocytic leukemia, and DLBCL. However, their mechanisms of action remain unclear. We broadly assessed the presence and mechanisms of suppression of MDSC subsets in DLBCL. First, a myeloid suppressive signature was identified by gene expression profiling in DLBCL peripheral blood. Accordingly, we identified, in a cohort of 66 DLBCL patients, an increase in circulating G-MDSC (Lin(neg)HLA-DR(neg)CD33(pos)CD11b(pos)) and M-MDSC (CD14(pos)HLA-DR(low)) counts. Interestingly, only M-MDSC number was correlated with the International Prognostic Index, event-free survival, and number of circulating Tregs. Furthermore, T-cell proliferation was restored after monocyte depletion. Myeloid-dependent T-cell suppression was attributed to a release of interleukin-10 and S100A12 and increased PD-L1 expression. In summary, we identified expanded MDSC subsets in DLBCL, as well as new mechanisms of immunosuppression in DLBCL.

In cancer, infection and inflammation, the immune system’s function can be dysregulated. Instead of fighting disease, immune cells may increase pathology and suppress host-protective immune responses. Myeloid cells show high plasticity and adapt to changing conditions and pathological challenges. Despite their relevance in disease pathophysiology, the identity, heterogeneity and biology of myeloid cells is still poorly understood. We will focus on phenotypical and functional markers of one of the key myeloid regulatory subtypes, the myeloid derived suppressor cells (MDSC), in humans, mice and non-human primates. Technical issues regarding the isolation of the cells from tissues and blood, timing and sample handling of MDSC will be detailed. Localization of MDSC in a tissue context is of crucial importance and immunohistochemistry approaches for this purpose are discussed. A minimal antibody panel for MDSC research is provided as part of the Mye-EUNITER COST action. Strategies for the identification of additional markers applying state of the art technologies such as mass cytometry will be highlighted. Such marker sets can be used to study MDSC phenotypes across tissues, diseases as well as species and will be crucial to accelerate MDSC research in health and disease.

Follicular lymphoma (FL) B cells contract tight connections with their microenvironment, which governs the pathogenesis and progression of the disease. Indeed, specific immune response gene signatures, obtained from whole biopsy samples, have been associated with patient survival. In this study, we performed gene expression profiling of purified B cell and non-B cell compartments obtained from FL and reactive lymph nodes. We identified 677 non-redundant genes defining the FL interface and involving 26 FL-specific functional networks. This approach highlighted an interleukin-4 (IL-4)-centered pathway associated with an activation of signal transducer and activator of transcription 6 (STAT6), which favors overexpression of IL-4-target genes. In addition, FL microenvironment was characterized by a strong enrichment in follicular helper T cells (T FH ), as demonstrated through transcriptomic and flow cytometry analyses. The majority of phospho-STAT6 pos B cells were located at the vicinity of cells expressing the programmed death 1 (PD-1) T FH marker. Moreover, purified FL-derived T FH , expressed IL4 at very high levels compared with purified tonsil-derived T FH or non-T FH microenvironment. Altogether, our study demonstrated that tumorinfiltrating T FH specifically express functional IL-4 in FL, creating an IL-4-dependent T FH -B cell axis. This cross talk could sustain FL pathogenesis and represent a new potential therapeutic target.

No abstract

A Complete Blood Count performed by an automated hematology analyzer frequently needs a microscopic slide review. This step is time consuming and requires experienced personnel. Recently, several teams have proposed and validated convenient combinations of monoclonal antibodies for an extended white blood cell (WBC) differential by flow cytometry. The aim of this study was to evaluate the usefulness of this approach in the routine workflow of a hematology laboratory. We compared a workflow chain comprised of a robotic blood preparation system (for antibody labeling), a flow cytometer, and data management software to the standard manual review of a blood film and evaluated the diagnostic quality, the turnaround time, and the labor needed for the two different approaches. The study on 1,973 samples was organized, firstly, to determine analytic thresholds and these settings were then validated. The flow cytometric data management software automatically validated 52% of the samples without significant numbers of false negatives. Of the remaining specimens, an operator validated a further 33% of the samples and 15% needed a manual microscopic review. These results were obtained in a mean timeline similar to the traditional microscopic manual review. Our study demonstrates, for the first time, the efficiency of a flow cytometer integrated into a WBC differential workflow in a routine hematology laboratory. ' 2010 International Society for Advancement of Cytometry

STAT3 mutations have been described in 30-40% of T-large granular lymphocyte (T-LGL) leukemia patients, leading to STAT3 pathway activation. Considering the heterogeneity of the disease and the several immunophenotypes that LGL clone may express, the aim of this work was to evaluate whether STAT3 mutations might be associated with a distinctive LGL immunophenotype and/or might be indicative for specific clinical features.Our series of cases included a pilot cohort of 101 T-LGL leukemia patients (68 CD8+/CD4- and 33 CD4+/CD8±) from Padua Hematology Unit (Italy) and a validation cohort of additional 20 patients from Rennes Hematology Unit (France).Our results indicate that i) CD8+ T-LGL leukemia patients with CD16+/CD56- immunophenotype identify a subset of patients characterized by the presence of STAT3 mutations and neutropenia, ii) CD4+/CD8± T-LGL leukemia are devoid of STAT3 mutations but characterized by STAT5b mutations, and iii) a correlation exists between STAT3 activation and presence of Fas ligand, this molecule resulting highly expressed in CD8+/CD16+/CD56- patients. Experiments with stimulation and inhibition of STAT3 phosphorylation confirmed this relationship. In conclusion, our data show that T-LGL leukemia with specific molecular and phenotypic patterns is associated with discrete clinical features contributing to get insights into molecular bases accounting for the development of Fas ligand-mediated neutropenia.